Treatment of hydrocarbon fuels



April 13, 1954 D. T. ROGERS ET AL TREATMENT OF HYDROCARBON FUELS Filed Nov. l, 1951 uioN. M1OF J|QQ @1F51 WON.. @m .fm OQ Al A' Tdjw. @ir dOkOE M2 :2((d-FM e lm 2MJ IPU VMWI MN. .I1 NN a a AMO y L! :(3, mm wzwhwwdd :um @2.551 O@\ k A|| A W Nw .IIY lMII LI OJ All f@ @Nk Owl om/ @S @q f om T @J T o #M lmjh. Ama N ZOCNMJWPWDV 0F05 lv @I1 H C Dumb m w@ b a a C @o am n a W er. www, Kr. ./@7 Hw www UUUUQ do@ @2 .mloN

Patented Apr. 13, 1954 TREATMENT OF HYDROCARBON FUELS Dilworth T. Rogers, Summit, and Roy V. High,

Jr., Union, N. J., assignors to Standard Oil Development Company, a corporation of Dela- Ware Application November 1, 1951, Serial No. 254,234

4 Claims.

The present invention is concerned with an improved process for the production of high quality petroleum products employing a treating agent comprising hexamethylene tetramine. The invention is particularly concerned with the production of a high quality heating oil product secured from a catalytic cracking operation by treating the heating oil product with formaldehyde and ammonia under conditions to form hexamethylene tetramine.

As pointed out heretofore, the invention is broadly concerned with the production of high quality petroleum products, particularly those boiling in the motor fuel and heating oil boiling ranges by contacting the same with hexamethylene tetramine. The invention especially is concerned with the production of an improved heating oil product secured from a catalytic cracking operation. These products are hydrocarbon mixtures known as fuel oils of the nature employed in various burner systems, as diesel fuels, or as domestic and industrial heating oils. Fuel oils may be derived from petroleum by a variety of methods including straight distillation from crude petroleum oil, and thermal or catalytic cracking of petroleum oil fractions.

However, it has been found that fuel oils consisting completely or in part of cracked stocks are characterized by an undesirable instability giving rise to the formation of sediment. As a result, such fuel oils may cause clogging of filters, orifices, or conduits associated with the burning systems in which they are employed.

In accordance with the present invention it has been established that the instability of cracked heating oils may be substantially overcome by treating the heating oil with formaldehyde and ammonia under -conditions to form hexamethylene tetramine. Heating oils which may be stabilized by these additives are hydrocarbon mixtures of which more than about 10% consist of stocks derived from thermal or catalytic cracking operations. More precisely still, the base stocks may be characterized as petroleum fractions containing a proportion of cracked stocks greater than 10% and falling within A. S. T. M. specification D-975-50T for Diesel Fuel Oils (Grades No. l-D to 4-D inclusive) and A. S. T. M. specioation D-396-48T for Fuel Oils (Grades No. l to 6 inclusive) or the corresponding Commercial Standard Specifications for Fuel Oils (CSM-48) of the U. S. Department of Commerce.

The present invention may be readily understood by reference to the drawing illustrating embodiments of the same. Referring specifically to the drawing, a feed oil which for the purpose of illustration is assumed to be a crude oil is introduced into distillation zone I0 by means of feed line I. Temperature and lpressure conditions in zone l0 are adjusted to remove overhead by means of line 2 gases and to remove by means of line 3 hydrocarbon constituents boiling in the motor fuel boiling range (80-430 F.). Hydrocarbon constituents boiling above the motor fuel boiling range, in the gas oil boiling range (400 F.800 F.) are removed by means of line 4 While higher boiling fractions are removed by means of line 5. It is to be understood that distillation zone I0 may comprise any suitable number and arrangement of stages.

The hydrocarbon fraction boiling in the gas oil boiling range is passed to a cracking zone 20 which for the purpose of illustration is assumed to be a catalytic cracking zone wherein the same is subjected to temperature and pressure conditions adapted to produce lower boiling hydrocarbon constituents. The cracked product is withdrawn from zone 20 by means of line Ii and passed into a distillation zone 30 wherein light hydrocarbon fractions are removed overhead by means of line l. Hydrocarbon fractions boiling in the motor fuel boiling range (80 llt-430 F.) are removed by means of line 8 While a hydrocarbon stream boiling in the heating oil boiling range is removed by means of line 9. Higher boiling fractions are removed by means of line II. In accordance with one concept of the present invention, the hydrocarbon fraction boiling in the motor fuel boiling range is passed to a treating zone 40 wherein the same is contacted with ammonia which is introduced by means of line I2 and withformaldehyde which is introduced by means of line I3. It may be desirable to first react the ammonia and formaldehyde and then introduce the reaction product into zone 40. If this mode of operation be carried out, the formaldehyde is introduced into the ammonia by means of line I5. The treated motor fuel fraction is withdrawn from treating zone 40 by means of line IE and introduced into a distillation zone 50. Hydrocarbons boiling below the motor fuel boiling range are removed overhead from zone 50 by means of line I l, while a treated fraction boiling in the motor fuel boiling range is removed by means of line I8. A reaction product and hyp drocarbon fractions boiling above the motor fuel boiling range are removed as a bottoms product by means of line I9. A preferred method of operation is to introduce at least a part of these products into line 9 by means of line 2 I.

The hydrocarbon fraction boiling in the heating oil boiling range is introduced into treating zone 50 by means of line 9 preferably in combination with the higher boiling constituents removed from zone 50. In zone the hydrocarbon fraction is treated with ammonia which is introduced by means of line 22 and with formaldehyde introduced by means of line 213. Here again it may be desirable to introduce the formaldehyde into the ammonium line by means of line 2 3 A preferred method of operation is to segresate the hydrocarbon fractions boiling in the motor fuel boiling range and the hydrocarbon fractions boiling in the heating oil boiling range from zene 30 as a single streamrbym'eans of lline This stream is then introduced into a treating zone 'it wherein the Isaine is Asubjected to treatment with ammonia which is introduced by means of line 25 and formaldehyde which is introduced by means of line 2l. The method of treatment is similar to thati desoribed'with re#- spect to zones i0 and 60. The treated fraction is withdrawn from zone-'i0 by means ofline 28 and passed to distillation zone 80 wherein hydrocarbons boiling below the motor fuel boiling range are removed by means of line 29. A hydrocarbon fraction boiling in the motor fuel boiling range is removed by means ofline 3l while a hydrocarbon fraction boiling in the heating oil boiling range is segregated by means of line 32. Higher boiling fractions are removed by means of line 33. The invention is broadly concerned vwith the production of stable, cracked hydrocarbon products'boiling below about '759 F. These cracked fuels may be obtained by thermal or by catalytic cracking of heavy petroleum stocks. The total eiiiuent from the cracking operation may be distilled into alight distillate boiling upto about 400 F. and into'a'heavier gas oil or fuel oil fraction. The light distillate is eminently suitable as a base stock for the prepara-tion of motor fuel while the gas oil o1 fuel oil fraction is used as fuel in domestic and industrial burner systems, diesel engines and various other industrial and domestic equipment. The light distillate produced in this manner is objectionable' in that it develops gum in Vstanding orv storage. rSuch gum deposits in internal combustion engine parts and aids in the formation of carbon and causes the sticking of valves. The light distillate lis also objectionable in that when incorporated without treatmentin motor gasoline, sludge'andvarnish deposits deleterious to satisfactory operation may be formed in the automotive engine. lIfhe heavier fuel oil fraction is alsosubject to similar disadvantages. Hydrocarbons, such as distillate fuels, for example,v those having a nor- Y mal distillation range ofV from about 300F. to about 700 F. and particularly from about 340 F. to about 640 F'. generally have a markedv tendency to deteriorate under oxidizing conditions,

and to form sludge, causing clogging and plugging of lters, strainers, screens, conduitlines, and the like, of the equipment in which they are used. This necessitates'frequent cleaning and even replacement of parts, thereby markedly decreasing the performance efficiency yof various equipment which `utilizes such fuel oils.

In accordance with the present invention, unexpected desirable results are securedV by treating the hydrocarbon fraction with aV minor amount'of hexamethylene tetramine orl a mixture of formaldehydeand ammonia to form hexamethylene tetramine .inv situ. While either the mixture of formaldehyde and ammonia or the hexarnethylene tetramine may Vbe used, it is usually more convenient to ruse thelatter since .it is a solid and can be more easily handled. The amount of Vhexamethylene tetramine employed may be from about 0.1 to about 5% by Weight of the fuel. Generally, 1 or 2% is sufficient even with very unstable fuels. In accordance with one preferred embodiment of this invention, the hexarnethylene tetramirie is added to the total 4 Y of line Bli'and the total effluent is distilled While in the presence of the hexamethylene tetramine to give a motor fuel fraction and a heavier fuel oil fraction which contains the hexamet'nylene tetramine Aas such'or as its reaction products. If this adaptation of the operation be carried out, thetreating of the fractions in zones d0,

S0 andv 10 is dispensed with. However, under some circumstances, it may be more desirable to treat motor fuel or other naphtha fractions with the addition agent separately. Likewise, the

addition agent may be added directly to a fuel oilfraction. In such cases, where the product is not to be subsequently distilled, it is generally desirable to subject it to a heat treatment, for example at 20D-500 F. for about 0.25 to 2.5 hours.

The hydrocarbon distillate fuel oils which may be treated in accordance with this invention may be treated or untreated (e. g. by hydrogenation, clay or bauxite, alkali washing and treating) fuels which have been thermally or catalytically cracked, thermally or catalytically reformed or hydrofcrmed or aromatized, or mixture of such fuels with straight-run fuels, which have an initial distillation point of about 90 F. and an end distillation point not exceeding 700 F. Generally these fuels have a boiling range of from about 340 F. to about 706 F. and preferablyV a boiling range of from about 400 F. to about 675 F. However, as pointed out, the invention is particularly adapted for the pro-duction of iinproved heating oil fractions secured from a iiuid catalytic cracking operation.

It is well known in the art to produce cracked naphthas and-other cracked products by a fluidized solids catalytic operation wherein the cracked product comprises constituents boiling in the motor fuel boiling range, as for example, below about L30" F. The cracked product also cornprises normally gaseous constituents, as for eX- ample, those containing three carbon atoms and less in the molecule. The uidized solids technique'for processing feed fractions, as for eX- ample, gas oils, heavy residuums and other feed stocksfor the'production of hydrocarbon fractions boiling inthe motor fuel boiling rangeV is a conventional one. For example, one system of a fluidized solids technique comprises a reaction zone and a regeneration zone, employed in conjunction with a fractionation zone. The reactor and the. catalyst regenerator are arranged at approximately an even level. The operation of the reaction zone and the regeneration zone is also conventional, which preferably is as follows:

Y An overflow pan is provided in the regeneration zone at the desired catalyst level. The catalyst overows into a withdrawal line which preferably has the form of a U-shaped seal leg connecting the regeneration zone with the reaction zone. The feed stream introduced is usually preheated to a temperature in the range from about 500 F. to 650 F. in exchangers in heat exchange with regenerator ilue gases which are removed overhead from the regeneration zone, or with cracked products. The heated feed stream is withdrawn from the exchangers and introduced into tbe reactor. The seal leg is usually sufficiently below the point of feed oil injection to prevent oil vapors from backing into the regenerator in case Vof normal surges. Since there is no restriction in the overflow line from the regenerator, satisfactory catalyst flow' will occur as long as the catalyst level in the reactor is slightly below the catalyst level in the regenerator when liquid effluent from the cracking unit, by means vessels are' carried at about the same pressure.

Spent catalyst from the reactor flows through a second U-shaped seal leg from the bottom of the reactor into the bottom of the regenerator. Thev rate of catalyst flow is controlled by injecting some of the air into catalyst transfer line to the regenerator.

The pressure in the regenerator may be controlled at the desired level by a throttle valve in the overhead line from the regenerator. Thus, the pressure in the regenerator may be controlled at any desired level by a throttle valve which may be operated, if desired, by a differential pressure controller. If the pressure differential between the two vessels is maintained at a minimum, the seal legs will prevent gases from passing from one vessel into the other in the event that the catalyst flow in the legs should cease.

The reactor and the regenerator may be de signed for high velocity operation involving linear superficial gas velocities of from about 2.5 to 4 feet per second. However, the superficial velocity of the upflowing gases may vary from about 1-5 and higher. Catalyst losses are miniinized and substantially prevented in the reactor by the use of multiple stages of cyclone separators. The regeneration zone is provided with cyclone separators. These cyclone separators are usually from 2 to 3 and more stages.

Distributing grids may be employed in the reaction and regeneration zones. Operating temperatures and pressures may vary appreciably depending upon the feed stocks being processed and upon the products desired. Operating temperatures are, for example, in the range from about 800 F. to 10=00 F., preferably about 850- 950 F., on the reaction zone. Elevated pressures may be employed, but in general, pressure below 100 lbs. per sq. in. gauge are utilized. Pressures generally in the range from l to 30 lbs. per sq. in. gauge are preferred. A catalyst holdup corresponding to a space velocity of 1 to 20 weights per hour of feed per weight of catalyst is utilized. A preferred ratio is 2 to 4. Catalyst to oil ratios of about 3 to 10, preferably about 6 to 8 by weight are used.

The catalytic materials used in the iluidized catalyst cracking operation, in accordance with the present invention, are conventional cracking catalysts. These catalysts are oxides of metals of groups II, III, IV and V of the periodic table. A preferred catalyst comprises silica-alumina wherein the weight per cent of the alumina is in the range from about 5 to 20%. Another preferred catalyst comprises silica-magnesium where the weight per cent of the magnesia is about 5% to 20%. These catalysts may also contain a third constituent, as for example, ThOz, W03, MOO, B80, BzOa, CdO, U03, B203, SIlOz, F6203, V205, MnO, CrzOa, CaO, T1203, MgO and CezOa present in the concentration from 0.05% to 0.5%. The size of the catalyst particles is usually below about 200 microns. Usually at least 50% of the catalyst has a micron size in the range from about 20-80. Under these conditions with the superficialvelocities as given, a uidized bed is maintained wherein the lower section of the reactor, a dense catalyst phase exists while in the upper area of the reactor a dispersed phase exists.

The present invention may be more fully understood by the following examples illustrating embodiments of the same.

Example 1 40 grams (2 wt. percent) of hexamethylene was added to 2500 cc. of afraction obtained by the catalytic cracking of gas oil and boiling in the approximate range of F. to 430 F. and the mixture distilled to a 400 F. vapor temperature. The overhead product was tested for cleanliness properties by means of a test which correlates with actual performance in internal combustion engines. In this test 600 gms. of the fuel is burned by means of an open blow torch ame having a burning-rate from 70 to 90 grams per hour and adjusted to give essentially complete combustion, thus simulating combustion in an internal combustion engine. The productsof combustion are brought into proximity with a cooled surface which acts as a collector for the deposits. A suitable collector is a condenser :having a glass or metal liner whose end is immediately adjacent the burner tip. The liner is suitably 3 inches in diameter and 12 inches long and is jacketed to permit water circulation. After the fuel is burned, the liner is washed with acetone to extract the deposits, the acetone solution is filtered and is evaporated to dryness. The weight of acetone-soluble deposits obtained in this manner correlates with the amount of deposits obtained when the fuel is burned in an internal combustion engine.

The results for the hexamethylene tetraminetreated gasoline are shown below compared with the results obtained on the untreated fuel:

Estimated Deposits in Diazonium Aeetone Solu- Fluoborate ble Deposits, Deposit Factor mg./600 gms. Engine Test,

The diazonium fluoborate deposit factor shown in the above table is an index of the engine cleanliness characteristics of a motor fuel. This test utilizes the coupling reaction which takes place between diazotised p-nitro aniline and certain unsaturated compounds (which cause engine fouling) to form a colored compound. Intensity of color formed after a given time interval is taken as an index of the deposit forming compounds present. In running the test, the fraction of the sample boiling over 275 F. and purified by treatment with dilute acid and alkali and steam distillation to 3% bottoms is used. A known quantity of this fraction is added to a solution of nitroaniline diazonium iluoborate (NO2C6H4N=NBF4) in acetone and the optical density measured at intervals in a Heilige-Diller emission photometer. The optical density is plotted against time and the value after 20 minutes reads from the curve. The optical density multiplied by the ratio of the fraction boiling over 275 F. to the whole sample gives the diazonium fluoborate deposit factor.

The above data indicate the superiority of the naphtha treated by the reagent of this invention, the estimated deposits in the engine test having been reduced from 167 %1 of reference to 71% of reference, compared to a relatively clean reference gasoline which was given a rating of 100. The improvement is even more striking when it is realized that the test was made about five weeks after the distillate has been treated with the hexamethylene tetramine. Previous studies have indicated that improvement in cleanliness characteristics was by other types of treatments only 7 temporary, ,and rwas' iost` after 30 days" storage. Thus, Y:the treatment of the present invention gives a storagestable product.

The bottoms produced inthe distillation of the original 2500cc. fraction usedfinY the above example and designated i as (400 R+) were mixed with heating oil to give a blend containing about 20% of the bottoms.

The resulting heating oil compositions were tested for stabilityin an accelerated sediment test, which indicates the tendency to form 'sediment in prolonged eld storageV and in which 600 grams of the heating oil was stored in a glass bottlev for a period of 16 hours While being maintained at a temperature of 210 F. At the end of this time, the heating oil was ltered and the amount of sludge accumulating during the storage period was then quantitatively determined. The results of these tests are indicated in the table below:

Accelerated diment, nig/600 g. Oil

heating o1 46. 9 20% (400 F.+) bottoms of fue! (treated with 2% hexamcthylene tetraminc) in 80% heating oil 27. 8

8 forming compoundsfrom a. cracked petroleum fuel which comprises contacting saidV fuel with about 0.1 to 2% by weight of hexamethylene tetramine andv thereafter` distilling said fuelA to remove the'reaction product as a bottoms.

2. Process according to claim'l in which the fuel is treated with amixture of formaldehyde and ammonia to form hexamethylene tetramine in situ.

3. Process for the production of a high quality motor fuel and a high quality heating oil which comprises contacting said motor fuel with about 0.1 to 2% by-Weight of hexamethylene tetramine, thereafter distilling said motor fuel to segregate the reaction product as a bottoms; adding said reaction product to said heating oil and contacting said heating oil withA about V0.1V to 2% by Weight of hexamethylene-tetramine 4. Process for the production of a high quality motor fuel and a high quality heating oil which comprises contacting said motor fue1 with about 0.1 to 2% by weight of hexamethylene tetramine, thereafter distilling `said motorfuel to segregate the reaction product as a bottoms, adding at least a portion of saldfreaction product to said heating oil.

References Cited inthe leof this patent UNITED STATES PATENTS Number Name Date 2,282,710 Y Dietrich May i12,y 1942 FOREIGN PATENTS Number v Country Date 636,332 `France Apr. 6, 1928 369,731 Great Britain 1932 

3. PROCESS FOR THE PRODUCTION OF A HIGH QUALITY MOTOR FUEL AND A HIGH QUALITY HEATING OIL WHICH COMPRISES CONTACTING SAID MOTOR FUEL WITH ABOUT 0.1 TO 2% BY WEIGHT OF HEXAMETHYLENE TETRAMINE, THEREAFTER DISTILLING SAID MOTOR FUEL TO SEGREGATE THE REACTION PRODUCT AS A BOTTOMS, ADDING SAID REACTION PRODUCT TO SAID HEATING OIL AND CONTACTING SAID HEATING OIL WITH ABOUT 0.1 TO 2% BY WEIGHT OF HEXAMETHYLENE TETRAMINE. 